The US Environmental Protection Agency (EPA) has a national rule about lead and copper concentrations in water that is designed to keep drinking water safe. But the regulation doesn't require testing of every tap.
"That's really the only safe drinking water rule we have right now that regulates lead in water," Megan Glover, co-founder of 120 Water Audit, told Business Insider.
Her company has tested the water at 4,000 day-cares and schools across the US.
"We tell our clients when we work with them: You should expect that over half, actually 65% of your facilities, are going to have an exceedance," Glover said.
However, the US has taken regulatory steps to improve public health and get rid of lead before. The phase-out of leaded gasoline and paint in the 1970s led to a measurable brainpower boost in kids: As blood-lead levels dropped, IQs went up between 2.2% and 4.7%.